add source-highlight variant to gdb (#15634)
add source-highlight variant to gdb (#15634)


LLNL/spack,LLNL/spack,LLNL/spack,iulian787/spack,iulian787/spack,LLNL/spack,iulian787/spack,iulian787/spack,iulian787/spack,LLNL/spack